The present invention relates to watercraft with steerable propulsion units and, more particularly, to a steering system for such a watercraft.
A watercraft equipped with a steerable propulsion unit can only be steered effectively when the propusiion unit is generating thrust. Examples of watercraft with a steerable propulsion unit are jet boats, personal watercraft, jet skis, and motorboats having swivel-mounted outboard motors. With any of these types of watercraft, the operator who releases the throttle loses the ability to effectively steer the watercraft. At low speeds, this typically makes docking difficult because it becomes necessary to open the throttle to maneuver the boat. Similarly, if the throttle is suddenly cut while running the watercraft at high speeds, the ability to steer can only be regained by re-opening the throttle.
U.S. Pat. No. 3,183,379 (Heidner) discloses a speed control device for use primarily on an outboard motor. When a motorboat that is either at rest or traveling at low speed is steered sharply (i.e. beyond a predetermined angle), a limiting rod interferes with the rotation of a throttle control member thereby limiting the RPM of the motor. The throttle control has a cam with a lobe that catches the limiting rod when the limiting rod is pressed against the cam. This prevents the boat from capsizing when the throttle is suddenly advanced and the motor is already set for a sharp turn. Since the danger of capsizing is significantly less when the boat is already traveling above a predetermined speed, the speed control device allows the motor to be swiveled through a full extent without actuating the limiting rod and interfering with the throttle control member. The predetermined speed (or RPM) above which the throttle control member becomes unconstrained by the limiting rod corresponds to an angular position of the cam at which the leading edge of the lobe has been rotated at least slightly beyond the line of action of the limiting rod.
U.S. Pat. No. 4,230,646 (Ghizzoni) discloses a carburetor device having a compensating membrane and a fuel accumulating chamber which is connected through conventional idling and high-speed jets to a Venturi upstream from which there is provided an air intake manifold. Externally of the compensating membrane is a sealed chamber which communicates via a flexible tube with a compensating chamber which is maintained naturally or artificially at atmospheric pressure.
U.S. Pat. Nos. 5,368,510 and 5,538,449 (Richard) disclose a trolling valve safety device that locks or limits actuation of a boat engine throttle from its idle position.
U.S. Pat. No. 5,423,277 (Gai) discloses a safety device for helm, throttle and directional controls of watercraft which prevents a boat from perilously spiraling into a man thrown overboard by ensuring that the rudder does not flop to one side under normal water flow pressure.
U.S. Pat. No. 5,256,092 (Jones) discloses a carburetor-adjusting accessory harness for personal jet-propelled watercraft. This removably mounted harness enables one to finely tune the carburetor while the watercraft is operating unanchored and afloat without having to remove the hood.
U.S. Pat. No. 5,253,604 (Bohlin) discloses an electro-mechanical steering device, especially for boats, that comprises an electronic control unit capable of comparing an actual position signal generated by the steering wheel to a predetermined position signal and thus actuating a servo motor in accordance with the difference between said signals.
U.S. Pat. No. 5,090,929 (Rieben) discloses a paired motor system for small boat propulsion and steerage. Two spaced-apart electrically driven motors, which are variable, reversible and separately controllable by a joystick-type controller, provide differential propulsion for improved steering and maneuverability.
French Patent 2 687 364 (Cany et al) discloses an ergonomic, simplified control device for operating an outboard motor. A plurality of control cables links the outboard motor with a single, centrally mounted control stick.
U.S. Pat. No. 5,016,553 (Spencer) discloses a vector steering control system that features at least one thruster mounted transversely (perpendicular) to the stern drive propeller shaft. Turning of the steering wheel activates one of the thrusters whose thrust accelerates the stern of the boat in a direction perpendicular to the stern drive shaft.
U.S. Pat. No. 4,962,717 (Tsumiyama) discloses a control stick that allows a boat to be both steered and accelerated with a single hand.
European Patent Application 388 228 (Glen) discloses a control apparatus for controlling a plurality of outboard motors with a single tiller. The tiller has a twist grip that winds the control cables around a drum so that the throttle of each motor can be controlled by a positive pullxe2x80x94pull action.
U.S. Pat. No. 4,854,902 (Havins) discloses a boat speed and direction control system for controlling trolling motors which is operable in a hands-free manner so that a lone fisherman operating a craft equipped with such a system would not have to relinquish control of his rod and reel.
U.S. Pat. No. 4,739,236 (Burkenpas) discloses a portable helm that comprises a hand-held controller that can be plugged into multipin connector-sockets wired at various locations on the ship. The hand-held controller is able to control the angle of the rudders, the engine RPM and the direction of the power train (i.e. forward, neutral or reverse).
U.S. Pat. No. 3,976,026 (Eastling) discloses a slow-speed steering control for jet-powered watercraft having a steering plate (similar to a rudder) mounted parallel to, but beneath, the deflector plates that vector the thrust of the water exiting the exhaust port of the jet propulsion unit. The steering plate is mounted to, and moveable with, the deflector plates such that when the deflector plates are angled (by turning the steering wheel or handlebars) the steering plate moves as well. The steering plate is submerged so that it assists the steering of the boat when the deflector plates are turned. Even when no flow of water is exiting the jet propulsion unit, the submerged steering plate still produces a steering effect when the steering wheel or handlebars are turned. The steering plate is resiliently mounted to the deflector plates so that if the underside of the steering plate collides with land, the steering plate will rise.
U.S. Pat. No. 3,874,321 (Smith) discloses a boat steering and reversing system. This system provides a mechanism for rotating the propulsion unit about a vertical axis by means of a steering mechanism for normal steering and combining with this arrangement a reversing changeover control capable of rotating the propulsion unit by 180 degrees. The mechanism uses a throttle idler or clutch control to effect the changeover.
As evinced by the foregoing survey of related prior art, the closest prior art appears to be a watercraft adapted to carry a rudder on the underside of its hull. Such a rudder allows the watercraft to be maneuverable even when the steerable propulsion unit is not generating any thrust. However, such a rudder is unsuitable for many jet boats, personal watercraft, jet skis and motorboats because they preclude these watercraft from operating in shallow waters which is where these watercraft are commonly used. The rudder also precludes such a watercraft from being xe2x80x9cbeachedxe2x80x9d without risking damage to the rudder.
Thus, there is a need in the industry for an improved steering system for a watercraft equipped with a steerable propulsion unit.
It is thus an object of the present invention to provide an improved steering system for a watercraft equipped with a steerable propulsion unit.
It is another object of the present invention to provide a watercraft that can be steered effectively when the manual throttle control is off.
It is another object of the present invention to provide a watercraft whose throttle is coupled to the steering of the watercraft so that the throttle is opened when the watercraft is steered.
It is another object of the present invention to provide a watercraft with steer-responsive throttle.
As embodied and broadly described herein, the present invention seeks to provide a watercraft comprising:
(A) a hull having a cockpit for accommodating an operator;
(B) a steerable propulsion unit drive by an internal combustion engine, said unit capable of generating thrust and capable of steering said watercraft by directing said thrust in a desired direction;
(C) a manual throttle control for controlling a throttle of said internal combustion engine;
(D) a manual steering control for steering said watercraft; and
(E) a throttle actuator responsive to said manual steering control for causing said steerable propulsion unit to generate a propulsive force at least equal to the minimum propulsive force necessary to effectively steer said watercraft when said manual steering control is turned in either direction beyond a predetermined angular threshold, whereby to cause said watercraft to remain maneuverable independently of the manual throttle control setting.
When the manual steering control is turned beyond a certain, predetermined angular threshold, the throttle actuator opens the throttle such that the propulsive force generated by the steerable propulsion unit is increased to a level corresponding to the minimal propulsive force needed to effectively steer the watercraft. This augmentation of propulsive force only occurs if the manual throttle control is set to produce a propulsive force less than the minimal propulsive force required for effectively steering the watercraft. Otherwise, if the manual throttle control is set to produce a thrust exceeding the minimal propulsive force required to effectively steer the watercraft, the steer-responsive throttle will remain open at the level set by the manual throttle control. Of course, if the manual throttle control is then reduced to below the threshold setting, the steer-responsive throttle will remain open so as to produce the minimal propulsive force necessary to effectively steer the watercraft. Thus, whenever the manual steering control is turned beyond the angular threshold, the steer-responsive throttle automatically ensures that the steerable propulsion unit generates the minimal propulsive force necessary for effectively steering the watercraft. Thus, the watercraft is maneuvered more easily since a turning thrust is automatically generated.
It is another object of the present invention to provide a watercraft with a steer-responsive throttle controlled by an electronic control system.
As embodied and broadly described herein, the present invention seeks to provide a watercraft comprising:
(A) a hull having a cockpit for accommodating an operator;
(B) a steerable propulsion unit driven by an internal combustion engine, said unit capable of generating thrust and capable of steering said watercraft by directing said thrust in a desired direction;
(C) a manual throttle control for controlling said internal combustion engine;
(D) a manual steering control for steering said watercraft;
(E) a throttle actuator responsive to a signal for causing the steerable propulsion unit to generate a propulsive force at least equal to the minimum propulsive force necessary to effectively steer said watercraft for a given speed when said manual steering control is turned in either direction beyond a predetermined angular threshold, whereby to cause said watercraft to remain maneuverable independently of the manual throttle control setting.
(F) a steer angle measuring device for generating a steer angle signal representative of the steer angle of said steerable propulsion unit;
(G) a speed measuring device for generating a speed signal representative of the speed of the watercraft;
(H) a throttle actuator control circuit for generating an output signal for controlling said throttle actuator; said throttle actuator control circuit having:
a first input for receiving said steer angle signal;
a second input for receiving said speed signal; and
an output signal generator for generating an output signal in response to signals received at said first and second inputs; said output signal being applied to said throttle actuator for controlling said throttle actuator.
This steer-responsive throttle further incorporates an electronic control system that senses the steer angle of the manual steering control as well as the speed of the watercraft and then computes a throttle setting that corresponds to a propulsive force appropriate for steering the watercraft.
Other objects and features of the invention will become apparent by reference to the following description and the drawings.